1. Preheat oven to 350 degrees F. Grease 2 large cookie sheets.2. Prepare the Dough: In a large bowl, with a spoon, mix all dough ingredients until smooth. 3. Drop dough by heaping tablespoons, 2 inches apart, on each prepared cookie sheet. There will be 12 rounds per sheet. 4. Bake 12 to 14 minutes. With a wide spatula, transfer cookies to wire racks to cool completely. 5. Prepare Marshmellow Creme Filling: In a large bowl, with mixer at medium speed, beat butter until smooth. Reduce speed to low; gradually beat in confectioners' sugar. Beat in marshmallow creme and vanilla until smooth. 6. Spread 1 rounded tablespoon filling on flat side of 12 cookies. Top with remaining cookies.